Faculty Collaboration Database

Cation-independent mannose 6-phosphate receptor: a composite of distinct phosphomannosyl binding sites. J Biol Chem 2009 Dec 11;284(50):35215-26

Date

10/21/2009

Pubmed ID

19840944

Pubmed Central ID

PMC2787381

DOI

10.1074/jbc.M109.056184

Scopus ID

2-s2.0-71749085682 (requires institutional sign-in at Scopus site)   64 Citations

Abstract

The 300-kDa cation-independent mannose 6-phosphate receptor (CI-MPR), which contains multiple mannose 6-phosphate (Man-6-P) binding sites that map to domains 3, 5, and 9 within its 15-domain extracytoplasmic region, functions as an efficient carrier of Man-6-P-containing lysosomal enzymes. To determine the types of phosphorylated N-glycans recognized by each of the three carbohydrate binding sites of the CI-MPR, a phosphorylated glycan microarray was probed with truncated forms of the CI-MPR. Surface plasmon resonance analyses using lysosomal enzymes with defined N-glycans were performed to evaluate whether multiple domains are needed to form a stable, high affinity carbohydrate binding pocket. Like domain 3, adjacent domains increase the affinity of domain 5 for phosphomannosyl residues, with domain 5 exhibiting approximately 60-fold higher affinity for lysosomal enzymes containing the phosphodiester Man-P-GlcNAc when in the context of a construct encoding domains 5-9. In contrast, domain 9 does not require additional domains for high affinity binding. The three sites differ in their glycan specificity, with only domain 5 being capable of recognizing Man-P-GlcNAc. In addition, domain 9, unlike domains 1-3, interacts with Man(8)GlcNAc(2) and Man(9)GlcNAc(2) oligosaccharides containing a single phosphomonoester. Together, these data indicate that the assembly of three unique carbohydrate binding sites allows the CI-MPR to interact with the structurally diverse phosphorylated N-glycans it encounters on newly synthesized lysosomal enzymes.

Author List

Bohnsack RN, Song X, Olson LJ, Kudo M, Gotschall RR, Canfield WM, Cummings RD, Smith DF, Dahms NM

Authors

Nancy M. Dahms PhD Professor in the Biochemistry department at Medical College of Wisconsin
Linda J. Olson PhD Assistant Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Binding Sites
Carbohydrate Conformation
Carbohydrate Sequence
Glucuronidase
Humans
Mannosephosphates
Microarray Analysis
Molecular Sequence Data
Phosphorylation
Polysaccharides
Receptor, IGF Type 2